The present invention relates to foam materials used for example in insulation, shock absorption, cushioning, packaging, sealing, lubrication, liquid absorption, liquid conducting, filtration of liquid, heat and gas insulation, providing buoyancy, gas absorption packaging and storage. The invention relates to foam materials with open pores as well as to foam materials with closed pores. Specifically, the present invention relates to elastic foam materials.
Foam material and in particular foam materials comprising olefinic polymers are well known in the art and enjoy widespread usage throughout the industry. Typical areas of application of such foam material include hygienic articles and in particular disposable absorbent articles, packaging materials.
Foam materials made from commonly used polyolefins such as PP, PE, PS, PIB have a number of useful properties. They are bio-compatible and food compatible, chemically stabile, inert, non toxic materials. However, most of them have poor mechanical properties including insufficient strength/tear resistance, insufficient stretchability/elasticity and the like.
Several approaches have been proposed in the prior art to provide elastic properties to such foam materials. The most commonly used approach is based on changing the chemical structure of the polymer by introducing hinged joints/moieties into the main chain of the polymer. These side groups or side chains provide more flexibility to the polymeric backbone preventing crystallization of polymer, lowering the glass transition temperature (Tg) and improving the elasticity of the resulting material. Usually, the hinge groups contain heteroatoms providing flexibility such as oxygen, nitrogen or chlorine placed into the main chain or into bulky side groups. Another approach is mastication of the polymer by blending with special plasticizing agents. Both approaches, however, require heteroatoms to be introduced into the molecule or into the bulk of the coating material.
The third approach proposed in the prior art to provide elastic properties to such foam materials, which is more close to the present invention, is to exploit the formation of hetero-phases which reinforce the bulk material by forming a physical net. To do this the block-co-polymerization of two or more different monomers has been used leading to polymeric backbones comprising blocks with different Tg. This results in micro-phase separation in the bulk with formation of reinforcing crystalline domains of one co-polymer linked with each other by flexible chains of the second co-polymer.
In essence, conventional foam materials carry a wide variety of inherent disadvantages including but not being limited to insufficient strength/tear resistance, insufficient stretchability/elasticity, not being bio-compatible, not being food compatible, comprising heteroatoms such as chlorine and hence leading to toxic residues when burnt, and the like.
It is an object of the present invention to provide foam materials which overcome the disadvantages of the prior art foam materials.
It is an further object of the present invention to provide articles which comprise elastic foam materials.
It is an further object of the present invention to provide a method for manufacturing foam material of the present invention.
It is a further object of the present invention to provide a foam material that can be manufactured with low variability between different batches of material.
The present invention provides a polymeric foam material. The foam material comprises a polyolefinic homopolymer having an isotacticity of less than 60% [mmmm] pentad concentration.
The present invention further provides a method for manufacturing the polymeric foam material of the present invention comprising a step of processing the polymeric material, said step of processing selected from the group of inert gas expansion, evaporated solvent expansion, reactive reagent gas expansion, high internal phase emulsion, bead expansion, and combinations thereof.